Climatology of polar lows impacting Norway

Type

Not peer reviewed

View/Open

Date

Author

Share

Metadata

Abstract

Polar lows (PLs), mesoscale cyclones in high latitudes, impacting
Norway are studied in this thesis. A climatology of PLs in the
Nordic seas for the period 1979-2015 is made, by applying a
cyclone detection and tracking algorithm to reanalysis data.
Western Svalbard, northwestern Russia, Novaya Zemlya and the
northern coast of Norway are found to be the areas with the most
landfall of PLs. PLs are found to reach areas designated to fishery
and oil platforms, the most affected fishery area being south of
Svalbard. A higher number of PLs is found to reach Norway
compared to previous climatologies, suggesting that other types
of cyclones might be included by the algorithm. The temporal
distribution of PLs making landfall in Norway shows a rather large
annual variability, with December, January and February as the
months with the most PL events. A sensitivity analysis shows that
more PLs making landfall in Norway is found for a forward shear
environment compared to a reversed shear environment, and that
a negative phase of the Scandinavian blocking is the most
favorable low-frequency atmospheric variability pattern for PLs
making landfall in Norway. A climatology of PLs in the Nordic seas
for future climate scenarios shows a reduction of PLs in the 21st
century, more prominent for a larger anthropogenic climate
forcing. The changes are however small compared to previous
climatologies on PLs.